Moistening tobacco and other organic products in bulk



P 1942- w. L. ATWOOD 2,294,887

MOSTENING TOBACCO AND OTHER ORGANIC PRODUCTS IN BULK Filed Jilly 2 2 1940 fi erzzor'l Jar/379252: wm, 20M; 0m, ma wm di g s.

Patented Sept. 8, 1942 MOISTENING TOBACCO, AND OTHER. B.-

GANIC PRODUCTS IN BULK Wilfrid 1.. Atwood, Richmond, v.., assignor to The Guardite Corporation, a corporation of II- linois Application July 22, 1940, Serial No. 346,871

' 2 Claims. (01. 131-140) This invention relates to a process for moistening tobacco and other organic products in bulk and more particularly to a process for moistening'tobacco in hogsheads and the like under high vacuum.

This invention is an improvement upon the process described in Patent No. 2,217,935, issued October 15, 1940, to Horace L. Smith, Jr., and

Lucian N. Jones.

In the process there described, tobacco in hogsheads is subjected to a vacuum' in excess of 29.5 inches (an absolute pressure below .5 inch of mercury) after which it is supplied with steam and water to reduce the vacuum. Furthermore, in the process there described it is contemplated that this cycle of vacuum plus steaming shall be repeated one or more times. Moreover, in the process of that application, after the pressure produced by the steaming operation had reached 1 a desired maximum, it was found advantageous to maintain a substantially constant pressure by reduced introduction of steam for an ,extended period.

On some occasions the process therein described failed to give'adequate results, especially on cold tobacco, the moisture content in the center of the hogshead not always being as high as that on the more external portionsthereof. Moreover, on practically all occasions the process therein described-produces a "slumping" of the tobacco. That is, the tobacco shrinks within the hogshead to considerably less thanits original volume. For example, it. the hogshead is stood on end it will frequently fall away from the top oi the hogshead as much as ten or twelve inches .after the treatment. v

I have now discovered that these difiiculties can be completely or in large measure overcome by controlling the rate of introduction of steam, particularly in the first heating period.

In the process oi the present invention th tobacco is placed within a vacuum chamber and evacuated in the normal manner until water within the tobacco has boiled and washed out the air from the tobacco in the chamber. At the end of this operation the absolute pressure within the container is generally ..between .10 and .35

inch of mercury. Under the previous operation steam was introduced to the chamber at the rate of twenty to twenty-five pounds per minute for each one thousand pounds of tobacco, the steam being intermixed with more than enough waterf to desuperheat it: This amount is generally about three to five pounds per minute-oi. water steam having an initial pressure oi'about eighty to one hundred twenty pounds per square inch gauge.

In accordance with the present process, the initial amount of steam introduced is reduced below five pounds per minute ,per' thousand pounds of tobaccoand, for the most eflicient operation of the process, to as little as .7 to 1 l pound of steam per minute for each thousand pounds of tobacco.

The introduction of the steam and water to the chamber, of course, raises the pressure therein and as the pressure is raised 1 have found that the rate of introduction of steam may be correspondingly increased so as to provide .a sub-. 'stantially constant linear velocity for the added steam, 1

1 The invention is illustrated diagrammatically in the drawing by a three-dimensional graph.-

.The coordinate l0 represents steam velocity which is denoted by a projection of any particular point within the diagram upon it. The coordinate l I represents the specific volume of steam and extends in reverse direction from the coordinate l2 representing the steamvrate in pounds, The solid line l3 represents any given steam velocity which is shown as substantially constant regardless of the steam rate or the steam volume. The dotted lines II and I5, which intersect with the line l3, indicate how the steam rate may be determined at any particular time from the steam velocity desired. Allthat is necessary for a particular determination,

'. with a known desired steam velocity, is toalter the steam rate as the pressure rises in accordance with changes in the specific volume of steam as shown by'a steam table. Regulation of the rate of steam maybe accomplished with any variable opening valve but is preferably accomplished by an automatic valve which may be regulated to give a predetermined steam velocity regardless V of steam pressure in the system.

Following this process moisture is better distributed throughout the hogshead of tobacco and the tendency to slump is reduced or eliminated. The reason for such change is not completely understood. It is believed that if steam is introduced too rapidly in the beginning it will deposit,

by condensation, films 01 water on the outer lay-- ers of the hogshead, which are too thick and whichtend to block oil? the interior of the hogshead from the iurther introduction of steam and water. Moreover, the water in that case appears to condense more upon the surface of the tobacco for twenty-five pounds per minute dry saturated It and has not time to-penetrate the interior of the leaf, thus tending to produce a soggy mass rather than one through which the moisture is uniformly dispersed. It is possible that by proceeding in accordance with the present process the water is absorbed chemically in the tobacco rather than left as freemoisture upon the surface.

As an example of the process, tobacco in hogsheads was placed in a cylindrical container, the hogsheads being left on their sides without removal of the wood, after which a vacuum was produced as rapidly as possible until the pressure had fallen to approximately 0.2 inch absolute, during which time the tobacco cooled a few degrees. Steam was then introduced beginning at a rate of 0.7 lb. per minute per thousand pounds of tobacco, and the rate being increased constantly to provide a substantially constant velocity of the ingoing steam. The rate should never exceed 12 lbs. per minute. The steam employed was at all times supplied with cold water in the manner described in said Smith and Jones application, Serial No. 180,987, filed December 21, 1937, the amount of water being more than enough to desuperheat the steam. The effect of the slow addition of steam in this manner was that the temperature as recorded in the center of the hogsheads of tobacco rose at a rate approxi mately corresponding to the increase in pressure in the chamber. The steaming was kept up until the pressure within the tank had risen to approximately 12 inches absolute, this taking about ten minutes. Normally, the steaming will be continued until the product, if tobacco, has reached a temperature of 125 to 175 F., preferably from 140 to 170 F. Thereafter the chamber was again evacuated until the pressure had. dropped to about 0.6 inch, after which steam was introduced at the normal rate of approximately 25 lbs. per

minute per hogshead until the pressure had again risen to about 12 inches absolute. cycle was then repeated once more after which the chamber was evacuated to about 6 inches and the vacuum broken. The more tightly packed the tobacco, the lower the absolute pressure employed in this stage.

The tobacco in the hogsheads was uniformly moistened and showed no signs of slumping.

It has been found advantageous in general to carry out as rapid a cooling as possible without causing flufllng after the first slow steaming operation. This rapid cooling appears to assist in theopening of the interstices of the tobacco and to assist in its conditioning. Steaming after the first cycle may be repeated at the slow rate, but in general it has not been found necessary or advantageous to do so.

The tobacco seems to be most susceptible to damage by too rapid steaming at the lowest pressures. It is therefore preferred that special care This latter be taken below pressures of 4 inches absolute, particularly below 1 inch absolute.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

What Iclaim as new, and desire to secure by Letters Patent, isz

1. The method of treating tobacco in hogsheads or the like which comprises producing a high vacuum thereon, reducing the vacuum by supplying to the tobacco saturated steam carrying finely divided particles of water at a rate less than 5 lbs. of steam per minute per thousand pounds of tobacco until the temperature of the tobacco has risen to a temperature of the order of to F., then rapidly cooling the tobacco by increasing the vacuum and then again supplying steam to the tobacco to decrease th vacuum, the second introduction of steam being at a rate considerably in excess of 5 lbs. of steam per minute per thousand pounds of tobacco.

2. The method of moistening an organic prodnot under vacuum which comprises subjecting the product inbulk to a high vacuum and supplying steam thereto to reduce the vacuum and to condense on and moisten the product by penetration from the outside thereof toward the center, the steam being supplied initially at a very low rate and being progressively increased at a faster rate, the rate of introduction of steam being for no substantial interval more than 12 5 lbs. per minute per thousand pounds of product.

WH-IF'RJD L. ATWOOD. 

